Electronic devices such as computers, laptops, personal video recorders (PVRs), MP3 players, game consoles, set-first boxes, digital cameras, and other electronic devices often need to store a large amount of data. Storage devices such as hard disk drives (HDDs) and digital versatile discs (DVDs) may be used to meet these storage requirements. As the size of these devices decreases, heat dissipation has become more problematic.
Referring now to FIG. 1A, hard disk drive (HDD) 10 includes a hard drive assembly (HDA) printed circuit board assembly (PCBA) 14. A buffer module 18 stores data that is associated with control of the HDD 10. The buffer module 18 may employ SDRAM or other types of low latency memory. A processor 22 that is arranged on the HDA PCBA 14 performs processing that is related to the operation of the HDD 10. A hard disk control module (HDC) 26 communicates with an input/output interface 24 and with a spindle/voice coil motor (VCM) driver module 30 and/or a read/write channel module 34.
During write operation, read/write channel module 34 encodes the data to be written via a read/write device 59, as described in detail hereinbelow. The read/write channel module 34 processes the signal for reliability and may include, for example, error correction coding (ECC), run length limited coding (RLL), and the like. During read operation, the read/write channel module 34 converts an analog output of the read/write device 59 to a digital signal. The converted signal is then detected and decoded by known techniques to recover the data written on the HDD.
As can be appreciated, one or more of the functional blocks of the HDA PCBA 14 may be implemented by a single integrated circuit (IC) or chip. For example, a first integrated circuit 1C-1 may include the buffer module 18 and the processor 22. A second integrated circuit 1C-2 may implement the HDC module 26, the spindle VCM module 30, the read write channel module 34 and/or the I/O interface 24. Still other component combinations may be implemented as integrated circuit(s). For example, the processor 22 and the HDC module 26 may be implemented by a single integrated circuit. The spindle/VCM driver module 30 and/or the read/write channel module 34 may also be implemented by the same integrated circuit as the processor 22 and/or the HDC module 26.
A hard drive assembly (HDA) case 50 provides a housing for one or more hard drive platters 52, which include a magnetic coating that stores magnetic fields. The platters 52 are rotated by a spindle motor 54. Generally the spindle motor 54 rotates the hard drive platter 52 at a fixed speed during the read/write operations. One or more read/write arms 58 move relative to the platters 52 to read and/or write data to/from the hard drive platters 52. The spindle/VCM driver module 30 controls the spindle motor 54, which rotates the platter 52. The spindle/VCM driver module 30 also generates control signals that position the read/write arm 58, for example using a voice coil actuator, a stepper motor or any other suitable actuator.
The read/write device 59 is located near a distal end of the read/write arm 58. The read/write device 59 includes a write element such as an inductor that generates a magnetic field. The read/write device 59 also includes a read element (such as a magneto-resistive (MR) element) that senses the magnetic field on the platter 52. A preamp module 60 amplifies analog read/write signals. When reading data, the preamp module 60 amplifies low level signals from the read element and outputs the amplified signal to the read/write channel device. While writing data, a write current is generated which flows through the write element of the read/write device 59 is switched to produce a magnetic field having a positive or negative polarity. The positive or negative polarity is stored by the hard drive platter 52 and is used to represent data.
Referring now to FIG. 1B, an exemplary DVD system 61. A DVD PCBA 62 includes a buffer 64 that stores read data, write data and/or volatile control code that is associated the control of the DVD system 61. The buffer 64 may employ volatile memory such as SDRAM or other types of low latency memory. Nonvolatile memory 66 such as flash memory can also be used for critical data such as data relating to DVD write formats and/or other nonvolatile control code. A processor 68 arranged on the DVD PCBA 62 performs data and/or control processing that is related to the operation of the DVD system 61. The processor 68 also performs decoding of copy protection and/or compression/decompression as needed. A DVD control module 70 communicates with an input/output interface 72 and with a spindle/feed motor (FM) driver 74 and/or a read/write channel module 76. The DVD control module 70 coordinates control of the spindle/FM driver 74, the read/write channel module 76 and the processor 68 and data input/output via the interface 72.
During write operations, the read/write channel module 76 encodes the data to be written by an optical read/write (ORW) or optical read only (OR) device 78 to the DVD platter. The read/write channel module 76 processes the signals for reliability and may apply, for example, ECC, RLL, and the like. During read operations, the read/write channel module 76 converts an analog output of the ORW or OR device 78 to a digital signal. The converted signal is then detected and decoded by known techniques to recover the data that was written on the DVD.
A DVD assembly (DVDA) 82 includes a DVD medium 84 that stores data optically. The medium 84 is rotated by a spindle motor that is schematically shown at 86. The spindle motor 86 rotates the DVD medium 84 at a controlled and/or variable speed during the read/write operations. The ORW or OR device 78 moves relative to the DVD medium 84 to read and/or write data to/from the DVD medium 84. The ORW or OR device 78 typically includes a laser and an optical sensor.
For DVD read/write and DVD read only systems, the laser is directed at tracks on the DVD that contain lands and pits during read operations. The optical sensor senses reflections caused by the lands/pits. In some DVD read/write (RW) applications, a laser may also be used to heat a die layer on the DVD platter during write operations. If the die is heated to one temperature, the die is transparent and represents one binary digital value. If the die is heated to another temperature, the die is opaque and represents the other binary digital value. Other techniques for writing DVDs may be employed.
The spindle/FM driver 74 controls the spindle motor 80, which controllably rotates the DVD medium 84. The spindle/FM driver 74 also generates control signals that position the feed motor 90, for example using a voice coil actuator, a stepper motor or any other suitable actuator. The feed motor 90 typically moves the ORW or OR device 78 radially relative to the DVD medium 84. A laser driver 92 generates a laser drive signal based on an output of the read/write channel module 76. The DVDA 82 includes a preamp circuit 93 that amplifies analog read signals. When reading data, the preamp circuit 93 amplifies low level signals from the ORW or OR device and outputs the amplified signal to the read/write channel module device 76.
The DVD system 61 may further include a codec module 94 that encodes and/or decodes video such as any of the MPEG formats. A scrambler 97 may be used to perform data scrambling. Audio and/or video digital signal processors and/or modules 96 and 95, respectively, perform audio and/or video signal processing, respectively.